Radiant heat pump device and method

ABSTRACT

The present method and device is for configuring the geometry of a surface to emit highly non-diffuse radiant energy. When a target surface is placed in a region where it is targeted by the emitting surface, there can be a net heat flow from the surface emitting the radiant energy to the target surface, notwithstanding the target surface may be at higher temperature than the emitting surface. This method is employed in a radiant heat pump whereby the surface for emitting energy radiation surrounds a target. The temperature of the target, which is originally at a higher temperature than the temperature of the surface, can have further temperature increases as a result of the net heat flow thereby resulting in a useful temperature increase in the target&#39;s temperature. The target may then use the temperature increase to upgrade heat flowing through the target for use in industrial processes.

FIELD OF THE INVENTION

[0001] The invention relates to the field of radiant energy devices,heat transfer devices and methods and more particularly heat pumps.

BACKGROUND OF THE INVENTION

[0002] In industrialized countries, energy consumption is a fundamentalaspect of commerce and personal daily life. Global energy use is risingrapidly as other nations advance toward economic parity with theindustrialized world.

[0003] Until recently, the significant, observable negative consequencesof fossil fuel consumption were limited to relatively localized effectssuch as smog and acid rain. Now the majority of scientists believe thateven current consumption levels are contributing to changes in globalclimate which pose a high risk for the future stability of thebiosphere. This situation will worsen as consumption continues to grow.

[0004] The Kyoto Accord is the first international agreement intended tominimize the climate change impact of fossil fuel consumption byreducing the net emissions of carbon dioxide and other greenhouse gases(GHGs). To succeed, such initiatives must be supported by technologieswhich eliminate or significantly reduce the GHG emissions associatedwith fossil fuels. Alternative energy technologies, such as wind, solarand nuclear have made and continue to make energy supply contributionsat or near zero emissions. However, it will be decades before suchalternative energy technologies displace fossil fuels sufficiently totip the GHG balance. In the interim, measures to increase the efficiencyof energy use and fossil fuel conversion can help reduce GHG emissions.

[0005] Fossil fuels (primarily coal) are burned to generate a largefraction of the total electricity used worldwide. Consumption rates varywidely, but in North America, the monthly CO2 emissions associated withdomestic electricity use averages roughly three tonnes per household.Some geographic regions have coal reserves which are expected to lastmore than a century. Consequently, there is great incentive to continueburning coal despite its contribution to GHG emissions. Unfortunately,the steam cycles on which conventional coal-fired generating plants arebased run at net efficiencies below 40%. Most of the energy is releasedas waste heat into the environment when the steam is condensed.

[0006] As a result of trying to address these concerns and as a resultof rising energy costs, consumers at the industrial, commercial andresidential levels are seeking ways to reduce the quantities of energythey purchase and consume. One method that has been exploited with somesuccess in the last decade is the recovery and reuse of waste heat.Systems which harvest “free” renewable energy from the atmosphere,ground and large bodies of surface water have also become more common.Using the example above, such a system could recover energy from theeffluent of a coal burning generation plant to reduce waste heat.

[0007] The prior art teaches the recovery of waste heat using passiveheat exchange, chemical heat pumps, and vapour compression heat pumps(open or closed cycle heat pumps).

[0008] A brief discussion of each of these prior art systems and theirdeficiencies is as follows:

[0009] When the temperature of a waste heat source is high enough to bereused directly, passive heat exchange is almost always the mosteconomic method of recovery. However, most waste heat sources are wellbelow the temperature at which a need for energy exists elsewhere.Consequently, the scope for application of passive heat recovery isextremely limited. Industrially, most of these sources have already beenexploited.

[0010] Chemical heat pumps are limited to applications involvingtemperature ranges at which certain chemical reactions proceed atfavourable rates. This limits both the number of installations for whichthe technology is economic, and the flexibility of each installation toeconomically accommodate variations in operating conditions. Because ofthe nature of the chemicals used, chemical heat pumps are alsoundesirable for some applications. Perhaps the only advantage thatchemical heat pumps enjoy over their vapour compression counterparts isthe fact that their requirement for motive (electrical) energy input isa very small fraction of the total energy input.

[0011] By far the largest number of operating heat pumps in the worldare vapour compression heat pumps. Almost all vapour compression heatpumps are closed cycle units which recirculate a refrigerantcontinuously around a closed loop. The most common example of a vapourcompression heat pump is the refrigerator.

[0012] The major problems with vapour compression heat pumps lie incompressor technology (which is the heart of the vapour compressionpump) and the availability of suitable refrigerants.

[0013] More specifically, vapour compression heat pumps havehistorically been considered unreliable and are complex therebyrequiring maintenance. Many manufacturing companies are preoccupied withproduction-related equipment and therefore do not readily acceptperipheral equipment that might not work or cause operational problemsto other operating industrial systems. Further, manufacturing companiesdo not want peripheral equipment which requires specialized maintenanceskills.

[0014] Another problem specifically with closed cycle vapour compressionheat pumps is the necessity of handling, maintaining and using suitableworking fluids (refrigerants). Working fluids may be chemically unstableat temperatures high enough to be of interest, uneconomical or evenhazardous (explosive or toxic or both).

[0015] Open cycle heat pumps avoid the refrigerant problem associatedwith closed cycle units because they use the industrial process fluid asthe refrigerant. This eliminates the need for heat exchange with acaptive working fluid. However, there are several factors which severelylimit the range of applicability for open cycle units. For example,process liquids are sometimes corrosive or otherwise difficult tohandle, maintain and use which adds to the compressor cost. Further,process liquids are frequently mixtures of liquids which evaporate atdifferent temperatures and complicate the cycle. Still further, processliquids frequently contain dissolved or suspended solids, whichcomplicates some installations or makes them unworkable. Finally, opensystems are not well suited to heat recovery from waste liquids ascontamination of the working vapour with air is difficult to avoid andthereby limits cycle efficiency and economic attractiveness.

[0016] Open cycle heat pumps at high temperatures are subject to thesame compressor problems as their closed cycle counterparts. Both openand closed cycle systems are subject to the limitation that asubstantial amount of high cost electrical energy is required for vapourcompression. For economic closed cycle systems, the electrical energyinput can constitute up to one half of the total high temperature energythat the unit delivers. For well designed open cycle systems, theelectrical energy input can be as little as 7 or 8% of the deliveredheat. The cost of electricity relative to the costs of other energysources is a major factor in determining the economic viability of avapour compression installation.

[0017] There is consequently a need for a method of conserving energywhich improves the current art of heat transfer devices by providing asimple device and method for heat transfer which does not require vapourcompression or chemical reactions to recover energy from waste heatsources, and which achieves meaningful and useful temperature rises.

SUMMARY OF THE INVENTION

[0018] It is an object of the present invention to provide a method anddevice for increasing energy efficiencies by recovering heat which wouldotherwise be lost, and by raising the temperature of the heatsufficiently to permit use of recovered energy.

[0019] The present invention provides a method for exaggerating thenondiffuse emission pattern radiating from a surface by configuring thegeometry of the surface. This method can result in radiant heat fluxflowing in specific directions from the surface in a more concentratedor less concentrated pattern than for an ordinary surface having thesame composition and temperature. Another result of the method is thatthe apparent temperature of the surface as perceived from specificdirections is higher than or lower than the actual temperature of thesurface. Accordingly, if a receiving surface or target surface is placedin a region where the apparent temperature of the surface is higher thanthe actual temperature of the surface then the result is a net flow ofradiant heat from the surface (or emitting surface) to the targetsurface.

[0020] The net flow of radiant heat transfer can be further realized byminimizing the convective and conductive heat flow between the surfaceand the target surface (such that the combined heat flow by conductionand convection between the surface and the target surface is a smallfraction of the net heat flow by radiation between the surface and thetarget surface).

[0021] While this method is effective for a surface emitting to a targetsurface, one skilled in the art will appreciate that a plurality ofsurfaces can be used to emit radiant heat to the target surface. Aworker skilled in the art will further appreciate that the geometry ofthe surface or emitting surface can be configured in various ways. Inone method the geometry of the surface is configured to a V shape withthe opening of the V facing the target surface. Still further, thesurface can be made of various materials. In one method the material ishighly reflective and in a more specific embodiment the surface is ahighly polished metallic surface.

[0022] In one embodiment, entirely surrounding or nearly entirelysurrounding the target surface by a continuous surface or a plurality ofsurfaces further increases the effect of this method. In thisembodiment, by supplying heat to the emitting surface and removing heatfrom the target surface, the present invention provides a method forproducing a useful radiant heat pump.

[0023] The concept of the radiant heat pump is based on the fact thatradiant heat exchange between two bodies involves an independent andquantifiable flow of energy in each direction. This distinguishesradiant heat transfer from both conduction and convection, since atleast on a macroscopic scale, conductive and convective heat transferare uni-directional along a gradient. By producing an artificialenvironment in which the flow of radiant energy from an emitting surfaceat one temperature to a receiving surface at higher temperature isfavoured over the reverse and normally dominant flow, the inventionproposes to establish a net flow of radiant heat against a temperaturedifferential.

[0024] One method of producing the artificial environment is to modifythe geometry of the emitting surface such that its apparent temperature,from the perspective of the receiving surface, is higher than its actualtemperature. This may be achieved by modifying the geometry of theemitting surface such that its emissions are more focussed and lessdiffuse, and by orienting the emitting surface to emit a greaterconcentration of heat in the direction of the receiving surface. Theartificial environment can be further enhanced by eliminating conductiveand convective heat transfer by introducing a vacuum, for instance,which will also have the benefit of reducing scattering of the emissionsand interference with the radiant energy flow.

[0025] Radiant heat pumps overcome many of the major problems associatedwith other prior art systems since radiant heat pumps require nocompressor or other complex machines, require no chemicals orrefrigerants, can operate well over a wide temperature range, and can beassembled from a large number of identical components which can be massproduced at low cost.

[0026] Another advantage of radiant heat pumps is that they requireelectrical energy input only for pumping of the heat transport fluids,and not for operation (as in thermoelectric devices) or compression.Pumping of ordinary liquids is a very mature technology that industrywill have little difficulty implementing efficiently.

[0027] The radiant heat pump involves no refrigerants or other complexchemicals. Therefore, the practical and economic operating temperatureranges are not limited by chemical properties. The performance of eachpump is determined by its geometry, the characteristics of the emittersurfaces, and the quality of emitter surface preparation. It appearsthat a radiant heat pump will operate well over a far broadertemperature range than prior art heat pumps.

[0028] Perhaps the most important advantage of radiant heat pumps is thefact that radiant heat transfer is enhanced by increasing temperature.Since the rate of emission is proportional to the fourth power ofabsolute temperature, the attractiveness of the radiant heat pump overexisting technologies will typically increase with increasing sourcetemperature.

[0029] In accordance with the methods describe above, the presentinvention provides a radiant heat pump device for transferring heat froma surface to a receiving or target surface where the target surface hasa higher temperature than the emitting surface. The surface emits energyradiation towards the target surface. Further, the surface isgeometrically configured to project nondiffuse radiant emission patternstowards the target surface. The result, as apparent from the methodsdescribed above, is a net heat flow from the emitting surface to thetarget surface against a temperature differential.

[0030] In another embodiment of the radiant heat pump device, a hollowemitter assembly defines a vacuum-sealed enclosure. Passing through thehollow emitter assembly is a hollow cylindrical target for collectingradiation and for transporting the radiation to the exterior of theemitter assembly. The emitter assembly includes a plurality of emittingplates on the emitter assembly's inner surface, the emitter platesfacing the hollow cylindrical target and the emitter plates having asmooth surface for reflecting radiation emitted from the emitterassembly to the emitter plates to the hollow cylindrical target.

[0031] Other aspects and features of the present invention will becomeapparent to those ordinarily skilled in the art upon review of thefollowing description of specific embodiments of the invention inconjunction with the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Embodiments of the present invention will now be described, byway of example only, with reference to the attached Figures, wherein:

[0033]FIG. 1 is an emitter assembly including two emitter plates eachhaving an emitting surface in accordance with the invention;

[0034]FIG. 2 is a top view of the emitter assembly in FIG. 1 whichdemonstrates the reflection of emissions between two adjacentplate-emitting surfaces in -accordance with the invention;

[0035]FIG. 3 is a perspective view of an emitter assembly in relation toa target in accordance with the invention;

[0036]FIG. 4 is a graph which demonstrates the ratio of focussed fluxfrom an emitting surface compared to a theoretical blackbody flux inaccordance with the invention;

[0037]FIG. 5 is an emitter assembly in relation to a cylindrical targetin accordance with the invention;

[0038]FIG. 6A is a side view of one embodiment of the radiant heat pumpin accordance with the invention;

[0039]FIG. 6B is a cross sectional view of the radiant heat pump in FIG.6A taken at line A-A in accordance with the invention;

[0040]FIG. 6C is a cross sectional view of the radiant heat pump in FIG.6B taken at line B-B in accordance with the invention;

[0041]FIG. 6D is a cross sectional view of the radiant heat pump in FIG.6C taken at line C-C in accordance with the invention;

[0042]FIG. 7 is a cross sectional view of one embodiment of a radiantheat pump in accordance with the invention; and

[0043]FIG. 8 is a system of radiant heat pumps in accordance with theinvention.

DETAILED DESCRIPTION

[0044] Those skilled in the art will know that unlike heat conductionand convection, radiant heat transfer between two bodies involves anindependent, quantifiable flow in each direction. Conventional theory onradiant heat transfer is based on an ideal surface, known as theblackbody. The blackbody has a total emissive power which isproportional to the fourth power of its absolute temperature, emitsuniformly (diffusely) in all directions, emits with a characteristic,predictable wavelength distribution and absorbs all radiant energy whichis incident upon it.

[0045] A less idealized theoretical surface than a blackbody is termed agraybody which also emits diffusely and with a characteristic wavelengthdistribution. However, a graybody only emits a fraction of the power ofa blackbody; that fraction (uniform for all wavelengths) is termed itsemissivity. Conversely, a graybody also absorbs only a fraction of theincident radiant energy; that fraction (uniform for all wavelengths) isdefined as absorptivity (any incident energy not absorbed is reflecteddiffusely). Further, for a graybody, absorptivity is generally equal toemissivity.

[0046] Any two blackbodies or graybodies placed in line of sight contactwith each other will exchange radiant energy such that theirtemperatures tend to converge. That is, if one body has a highertemperature than the other body, then the amount of radiant energy fromthe higher temperature body which is transmitted to the lowertemperature body will be greater than the amount of radiant energy fromthe lower temperature body which is transmitted to the highertemperature body.

[0047] In contrast with blackbodies and graybodies, real surfaces haveemissivities and absorptivities which vary with wavelength, emit withdistribution patterns that deviate to varying degrees from trulydiffuse, and have reflections that are partly specular and partiallydiffuse. Accordingly, real surfaces will emit different amounts,generally less, radiant energy than blackbody or graybody surfaces.

[0048] The present invention provides a method and a device forexaggerating the nondiffuse emission patterns of real surfaces by makingradiant emissions from the surfaces less diffuse than the surfaces'normal emissions. As a consequence, the nondiffuse emission patterns canbe concentrated onto a receiving surface. Further, there can be a netflow of radiant heat energy from a lower temperature (emitting) surfaceto a higher temperature target or receiving surface. As described below,this method, which is contrary to the “nonmal” pattern considering thatthe vast majority of surfaces radiate heat diffusely, facilitates thenet transfer of radiant heat energy to the receiving surface against atemperature gradient, which has very valuable commercial uses.

[0049] In one embodiment of the method of exaggerating nondiffuseemission patterns shown in FIG. 1, two emitter plates 16, which eachhave the same dimensions and emitting surfaces 18, are placed in contactalong edges of equal length. Viewed in cross section (FIG. 2), the lineof contact forms the apex for a narrow, elongated “V” shape. In thisformation, the emissions from either plate 16 flowing in the generaldirection of the opening at the top of the V are confined and reflectedby the opposing emitting surface 18 of the plate 16 and are reflectedback toward the opening of the V.

[0050] The nature of the reflections of the emissions is of particularinterest. As shown in FIG. 2, the angle between a ray and the axis ofsymmetry 30 is smaller after the reflection than it is before thereflection, by an amount equal to the angle separating the plates 16. Inother words, each reflection is a sort of focussing event. Depending onthe geometry of the system and an emission's location of origin, anemission may undergo several more reflections before emerging from theopening of the V. If the plates 16 are sufficiently smooth, only atrivial amount of scattering takes place at each reflection.Consequently, a high percentage of the original emission is reflected.

[0051] The cumulative effect of multiple reflections to numerousemissions from the emitting surfaces 18 of this formation is a roughlyconcentrated beam of radiant heat energy whose component emissionsapproach with varying degrees of accuracy towards a direction parallelto the axis of symmetry 30.

[0052] Due to the unique emissivity characteristics of metals, a metalsurface is preferable for the emitting surfaces 18. More specifically,metals exhibit inverted emissivity characteristics (which increase atlow angles) and are far from diffuse. A highly polished metal surfacewill result in even less diffusion upon reflection of radiant heatenergy.

[0053] The combination of polished metal emitting surfaces 18 intocertain geometries causes the combined emitting surfaces 18 to projectnondiffuse radiant emission patterns. When compared with the radiantemission patterns produced by an ideal blackbody emitter, the totalemission of radiant energy from the emitting surfaces 18 will naturallybe equal to or less than the corresponding total for the ideal blackbodywith the same projected area. However, the emitting surface 18 projectsrelatively higher concentrations of radiant heat energy to specificregions and lower concentrations to other regions. That is, the radiantflux density projected along the axis of symmetry 30 for each emittingplate 16 pair is significantly higher than it would be in the case ofdiffuse emission but the flux densities at large angles from the axis ofsymmetry 30 are correspondingly lower. Accordingly, the emitting surface18 may achieve up to several times the equivalent blackbody emissionlevel for a target region and even greater emissions when compared to adiffuse emitter.

[0054] Using the method described above and adding a target plane 20which is perpendicular to the axis of symmetry 30 as shown in FIG. 3, itis possible to concentrate a beam of radiant heat energy from theemitting surface 18 on the target plane 20 (or a more specific target 31as shown in FIG. 5) which transmits more radiant energy towards thetarget plane 20 than if the emitting surface 18 was a normal diffuseemitting surface (or an ideal blackbody emitting surface).

[0055] The emitter assembly 14 is constructed so that the maximumrelative flux density from the emitter plates 16 is incident on or nearthe target 31. Consequently, from the target's perspective, the highradiant flux density makes the “apparent” temperature of the emitterplates 16 higher than the emitter plates' actual temperature. Since heatflow to the target 31 is based on the apparent temperature of theemitting surface as perceived by the target surface, the target 31 willabsorb more heat emitted from the emitter plates 16 than if the target31 was able to perceive the emitter plates' actual temperature.Accordingly, there will be a net flow of heat to the target 31,notwithstanding that the target 31 may be at a higher surfacetemperature than surface temperature of the emitter plates 16.

[0056] One method of maximizing heat transfer to a cylindrical target isto increase the number of pairs of emitter plates 16 oriented to projectfocussed emissions on the cylindrical target. This method can beembodied in the radiant heat pump device discussed below.

[0057] Another method to maximize the advantageous radiant transfer fromthe emitting surface 18 to the target 31 is to minimize the conductiveand convective “back flows” that occur as a result of the Zeroth Law.Conduction is minimized by limiting the cross-sectional area availablefor transfer back from the target 31 to the emitter plates 16.Convection is minimized by maintaining a vacuum between the emitting andtarget surfaces.

[0058] If undesirable heat losses by conduction and convection from thetarget 31 are minimized then the following equations describe therelationships between the temperatures of the target and emittingsurfaces and the rates of heat flow between the target and emittingsurfaces.

RAD _(t) =RAD _(e) −CONV  (i)

[0059] Where: RAD_(t) is the rate of radiant emission from the target,

[0060] RAD_(e) is the rate of radiant heat gain by the target, and

[0061] CONV is the rate of convective heat removal.

RAD _(t) =A _(t) E _(t) ST _(t) ⁴ ; T _(t)=(RAD _(t) /A _(t) E _(t) S)^(1/4)  (ii)

[0062] Where: E_(t) is the emissivity (absorptivity) of the target,

[0063] S is the Stefan-Boltzmann constant,

[0064] A_(t) is the surface area of the target, and

[0065] T_(t) is the absolute temperature of the target.

RAD _(e) =RA _(t) SE _(t) T _(e) ⁴  (iii)

[0066] Where: R is the ratio of incident emissions to blackbodyemissions, and

[0067] T_(e) is the temperature of the emitter plates.

[0068] Combining equations i, ii, and iii, and setting E_(t)=1:$T_{t} = \left( \frac{{{RA}_{t}{ST}_{e}^{4}} - {CONV}}{A_{t}S} \right)^{1/4}$

[0069] In the ideal case where: (1) the emitter assemblies 14 emit withthe power of blackbodies and (2) all emissions are incident on thetarget 31, the maximum concentration ratio that could be achieved wouldbe fixed by the geometry of the emitter assemblies 14.

[0070] The particular shape and arrangement of the emitting surfaces arevariable. For instance, the V shape shown in the figures may havevarious alternate configurations. More specifically, the angle of theopening of the V shape (shown as approximately 30° in FIG. 1) may benarrower or wider, the emitter plates 16 may have varying widths and theemitter plates 16 may not be planar. More generally, a V shape is notessential as other geometric configurations (having a plurality ofsurfaces where some surfaces may even emit diffusely) may achieve thesame purpose of exaggerating nondiffuse emission patterns to produceconcentrations of emitted energy toward a region or regions.

[0071] Using the above methods, it is possible to design a radiant heatpump 10.

[0072] In one embodiment shown in FIGS. 6A, 6B, 6C and 6D, the presentinvention provides a radiant heat pump 10 having a hollow shell assembly14 defining a vacuum sealed recess 15 and a hollow cylindrical target 12disposed through the emitter assembly 14 for collecting energy byradiation and for transporting the collected energy to the exterior ofthe shell assembly. In this embodiment the shell assembly 14 includes aplurality of emitting plates 16 on the shell assembly's inner surface17, the emitter plates 16 facing the hollow cylindrical target 12 andthe emitter plates 16 having a smooth active radiant surface or emittingsurface 18 for reflecting radiation transferred from the shell assembly14 to the emitter plates 16 and then by radiation to the hollowcylindrical target 12. The radiant heat pump 10 is designed to enclose avacuum such that conductive and convective heat transfer effects areinsignificant when compared to radiant heat transfer although any meansof minimizing conductive and convective heat transfer will be effective.

[0073] Although this embodiment is shown in two dimensions for the sakeof simplicity, a 3-D symmetry may also be used. For example, in anotherembodiment, the emitter assembly 14 may be spherical and the emitterplates 16 may define conical recesses for radiating focused emissions ona target 12 which, in such an embodiment, may also be spherical. Aworker skilled in the art will appreciate that other two-dimensional andthree-dimensional shapes will be effective.

[0074] In another or further embodiment, one skilled in the art willappreciate that the shell assembly 14 may be nested as shown in FIG. 7.That is, concentric shell assemblies (such that the outer surface of oneshell assembly forms the collector in another shell assembly, and soforth) may be provided around the hollow cylindrical (or spherical)target 12. Since emissive power is proportional to the fourth power ofabsolute temperature, higher source temperatures provided to the inneremitter assembly from the outer emitter assembly would make a radiantheat pump 10 more effective in terms of temperature lift to the target12.

[0075] In general operation, the radiant heat pump 10 is installed in anenvironment such as a generating plant or other energy facility whereheated liquid or steam is in contact with the outside of the radiantheat pump. Typically the liquid or steam is not at a high enoughtemperature for further use in the generating plant without upgradingthe temperature (that is, the heat is waste heat). As the heat or heatedwater comes into contact with the radiant heat pump 10, the exterior ofthe shell assembly 14 absorbs the heat and transmits the heat to theinterior surface 17 which includes emitter plates 16. Simultaneously,water or other heat energy removal means flows through the hollowcylindrical element 12. As a result of using the methods described aboveto modify the emitting surface 18 of the emitter plates 16 and to modifythe geometries of the emitter plates 16 to exaggerate the nondiffuseemission patterns of the emitter plates 16, the apparent temperature ofthe emitter plates 16 from the perspective of the cylindrical element 12is greater than the actual temperature of the emitter plates 16,resulting in the cylindrical element 12 absorbing more beat than ifcylindrical element 12 perceived the actual (lower) temperature of theemitter plates 16. Accordingly, there is a net flow of energy byradiation to the cylindrical element 12 which can raise the temperatureof the cylindrical element 12 to a useful temperature, notwithstandingthat the cylindrical clement 12 is at a higher temperature than emitterplates 16.

[0076] The emitter plates 16 may be long thin components formed, forexample, by machining, forging, stamping, die casting or investmentcasting. The material used is preferably strong, rigid, and economical,with a high thermal conductivity. In descending order of thermalconductivity, copper, aluminum and steel are among the best commonoptions currently available. If plastics, or composites with sufficientstrength and rigidity at high temperature exist in combination withadequate thermal conductivity, durability and very low gas permeability,they can also be used to construct the emitter plates 16. Thesecomposites may have a strength to weight advantage over metals. Suitableplastic forming techniques for forming the emitter plates includerotomolding, thermoforming, and if components are small enough, possiblyalso injection molding.

[0077] The emitter plates 16 are preferably solid and designed to directa substantial portion of emitted heat to the hollow cylindrical target12. A worker skilled in the art will appreciate that the emitter plates16 may be machined in one continuous piece thereby forming onecontinuous surface around the hollow cylindrical target 12.

[0078] The active radiant surface or emitting surface 18 is preferablyvery smooth. Due to the advantageous properties of polished metal withrespect to reflectivity described above, the emitter plates 16 arepreferably comprised of or coated with a polished metal surface 18.

[0079] Numerous design changes to the emitter plates 16 are conceivable.For instance, the emitter plates 16 may be curved and the emitter plates16 may include combinations of diffuse emitting materials and polishedmetals or other highly reflective materials. As stated above, theparticular shape and arrangement of emitting surfaces generally (andspecifically the emitter plates 16 in this case) is variable.

[0080] In addition to the emitter plates, the radiant heat pump 10 mayinclude reflecting surfaces at each end of the cylindrical or sphericalor other emitter surface 14 made of either flat or curved highlyreflective material. Alternatively, each end of the emitter assembly 14may include emitting surfaces made of either flat or curved surfacesthat emit diffusely. Still further, the end caps 22 may be composed ofcombinations of materials which emit diffusely and are highlyreflective.

[0081] In the embodiments described above, it is also possible toachieve refractive enhancement with materials that transmit thewavelengths of interest, if the effect of the materials used and thegeometries designed is to concentrate radiated energy from an emitter toa region including a collector.

[0082] The hollow cylindrical target 12 is used to transfer heatabsorbed by the target outside of the shell assembly 14 and on to a heatdelivery system (usually through fluid flowing through the hollowcylindrical element which is heated to a useful temperature byabsorption from the collector's surface). This upgraded energy can thenbe reused in a system (such as in FIG. 8) to achieve the objective ofconserving energy, recovering waste energy and reducing costs.

[0083] The hollow cylindrical target 12 is preferably not reflective(that is, the surface of the hollow cylindrical target 12 should behighly absorptive to maximize the net heat flow to the hollowcylindrical target 12). To achieve useful results, the surface area ofthe hollow cylindrical target 12 should be smaller than the apparent oreffective surface area of the emitter plates 16.

[0084] The artificial environment between the emitter assembly 14 andthe hollow cylindrical target 12 can help maximize the net flow of heatto the hollow cylindrical target 12 through the minimization of any backflow (from target to emitter) by conduction or convection. This may bedone, for instance, by vacuum sealing the emitter assembly 14 andminimizing contact of emitter and target by (for instance) providingheat insulation between those elements where they necessarily contacteach other or intermediate mounting means.

[0085] General immediate uses for the present invention are:

[0086] 1. waste energy recovery and upgrading, and process heat transferin industrial and large commercial applications, and

[0087] 2. condensing heat recovery from thermal power stations.

[0088] In addition to those areas in which the radiant heat pump willout-perform competitive technologies, the present invention can be usedin thermal-electric generating stations which currently wasteapproximately 40% of the total energy input by rejecting the energyinput as low temperature heat, usually to a nearby body of water. Thiswaste is the result of a thermodynamic limitation of the cycle used toconvert heat into mechanical energy. Steam is condensed at the outlet ofeach turbine and pumped back up to high pressure as water. To maximizethe efficiency of the generating cycle, this heat is rejected at as lowa temperature as possible and is not worth recovering. Radiant heatpumps could be used to recover some of this rejected waste heat forre-injection into the process to greatly increase the overall efficiencyof the plant. To optimize the recovery system, the discharge temperaturefrom the steam turbines would be increased from the normal ambienttemperature to perhaps 300 degrees C. The resulting small loss inefficiency of the existing cycle would be more than offset by therecovered heat. As already discussed, none of the existing heat exchangetechnologies are capable of effectively dealing with a source at thishigh temperature.

[0089] The availability of the present invention, particularly toindustry, may result in industry-specific applications that do notcurrently exist. As an example, in exchanging heat between two flows itmight be advantageous to transfer up in temperature rather than down asis currently the case with passive heat exchange. Depending on the costof production of the present invention, the present invention may, forexample, ultimately find application in building space heating (usingambient or very low temperature sources) or refrigeration.

[0090] One method of manufacturing and assembling a radiant heat pump isas follows:

[0091] After rough forming of the metallic components of the emitterplates 16, the mating surfaces that permit accurate relative positioningof adjacent emitter plates 16 are machined to high accuracy (˜+0.005″ orbetter). This precision is economical and practical with the currentgeneration of computer numerically controlled (CNC) machiningtechnology. Locating features such as tabs for position keying andgrooves for vacuum sealing elements between emitter plates may be addedduring the machining operation. In the same machining operation, or in aseparate machining or grinding operation, the surfaces of the emitterplates 16 that participate in the radiant exchange are finished to ahigh quality. The quality of surface finishing required for economicalperformance of the radiant heat pump, and the effect of directionalsurface markings left by machining or grinding on operation of the heatpump is determined empirically, and depends upon the material chosen andthe method of manufacture. However, if a higher surface quality of themetal emitter plates 16 is required, it maybe produced by secondaryoperations such as lapping and/or electropolishing.

[0092] Once each emitter has the correct shape, the emitting surfaces 18are coated with a thin film (likely <0.002″) of an appropriate material.Currently, the preferred materials are chromium or aluminum, howeverother materials that later prove to be more suitable are intended to beincluded herein. The coating technique depends upon economics, with apreference for the most economical coating method that providesacceptable radiant and reflective properties to the emitting surfaces18. Electroplating, which would be used for metals only, and vapourdeposition are among the most likely candidates for coating techniques.

[0093] If plastics or composites are used, the molding processes may bedesigned to minimize the amount and cost of work required after formingthe emitter plate 16. In particular, polished molds used with highperformance release agents might deliver active surface qualities readyfor the final coating.

[0094] Prior to assembly into the radiant heat pump 10, the emitterplates 16 are cleaned thoroughly and taken to an assembly area whichmeets clean room standards, not unlike those used for manufacture ofmicroelectronics. Completed emitter plates 16 are then stacked intocylindrical assemblies by placing them next to each other one unit at atime, and engaging the locating features until groupings spanning 180 oof arc are complete.

[0095] The next step in the assembly of the emitter assembly 14 is tocombine two half shells into a full cylindrical array of emitter plates16. The final step is to strap the array together with external hoops ofmetal or composite material. Vacuum sealing elements may be placedbetween emitters individually during assembly, or pumped through thesealing grooves in the entire array during a single step afterstrapping. In the latter case, the sealing material will harden to arigid state that provides additional mechanical stability to the emitterassembly 14, and helps to bond its components together. After bonding,straps may no longer be necessary. A sealing agent applied externally onthe emitter assembly 14 may further limit gas diffusion.

[0096] End caps 22 of machined metal or a composite material wouldcomplete each enclosure and its vacuum seals. The end cap 22 innersurfaces are preferably highly reflective to infrared wavelengths. Theend caps 22 also provide the connection point for vacuum lines (notshown), and possibly for reducing gases that would be flushed througheach chamber to accelerate the removal of surface oxide prior tostartup. As an additional requirement, each end cap 22 would provide abarrier to minimize thermal conduction between the shell assembly 14 andthe target 12 passing through its central port. At least one of the twoend cap-to-target joints would be allowed to slip relatively freely sothat differential thermal expansion of the target 12 would not place itin compression. Both would be thermally isolated such that the target 12is thermally insulated (for conduction) from the shell (and thus theemitters).

[0097] The hollow cylindrical target 12 may be a thin walled tube with athickness to diameter ratio <0.1 and with sufficient strength andrigidity to withstand the internal pressure of a fluid medium that flowsthrough the target 12 and conducts high temperature heat away from theradiant heat pump. The target 12 must also be sufficiently rigid tomaintain its concentricity in the assembly to an acceptable accuracy.Highly conductive metals, such as copper are potential materials fromwhich the target 12 may be comprised, however other materials are notintended to be excluded if they function as required in this invention.The convective performance inside the targets 12 may be enhanced byproviding the interior of the target 12 with turbulence inducinginserts, or by surface roughening of the interior wall of the target 12.The outside surface of each target 12 will be coated with a materialhaving a very high infrared absorbtivity.

[0098] Overall, the geometric parameters of the radiant heat pump 10 ofthis invention will preferably include:

[0099] 1. an emitter plate 16 separation angle of approximately 3° to12°;

[0100] 2. an emitter assembly 14 length to diameter ratio in the rangeof 2:1 to 6:1; and

[0101] 3. a ratio of shell assembly 14 inner diameter/target 12 outerdiameter of between 10:1 and 50:1.

[0102] If the rigidity of a composite or metal emitter assembly 14assembled according to the above methods proves inadequate, the emitterassembly 14 may be reinforced with an external metallic frame (notshown). This approach may prove to be more economical than the use ofmetallic emitter plates 16, particularly in the case of compositeemitters.

[0103] The above-described embodiments of the present invention areintended to be examples only. Alterations, modifications and variationsmay be effected to the particular embodiments by those of skill in theart without departing from the scope of the invention, which is definedsolely by the claims appended hereto.

What is claimed is:
 1. A method for exaggerating the nondiffuse emissionpattern radiating from a surface comprising the step of configuring thegeometry of the surface.
 2. A method as in claim 1 wherein the radiantheat flux flowing in specific directions from the surface is moreconcentrated or less concentrated than for an ordinary surface havingthe same composition and temperature.
 3. A method as in claim 2 whereinthe apparent temperature of the surface as perceived from specificdirections is higher than or lower than the actual temperature of thesurface.
 4. A method as in claim 3 wherein radiant heat is exchangedbetween the surface and a target surface, the target surface located ina region where the apparent temperature of the surface is higher thanthe actual temperature of the surface
 5. A method as in claim 4 whereinthere is a net flow of radiant heat from the surface to the targetsurface.
 6. A method as in claim 4 further comprising the step ofminimizing the convective and conductive heat flow between the surfaceand the target surface.
 7. A method as in claim 6 further comprising thestep of minimizing the convective and conductive heat flow between thesurface and the target surface such that the combined heat flow byconduction and convection between the surface and the target surface isa small fraction of the net heat flow by radiation between the surfaceand the target surface.
 8. A method as in claim 7 further comprising thestep of entirely surrounding or nearly entirely surrounding the targetsurface by at least one surface.
 9. A method as in claim 5 furthercomprising the steps of supplying heat to the surface and removing heatfrom the target surface.
 10. A method for exaggerating the nondiffuseemission pattern radiating from a surface comprising the steps ofconfiguring the geometry of the surface to a V shape.
 11. A method forconveying the apparent temperature of a surface to a target surfacewhere the actual temperature of the surface is lower than the apparenttemperature of the surface for ensuring a net flow of radiant heat fromthe surface to the target surface, comprising the steps of: configuringthe geometry of the surface to project nondiffuse radiant emissionpatterns into the region of the target surface; and providing thematerial of the surface with a highly reflective surface for improvingthe projection of nondiffuse radiant emission patterns.
 12. A method asin claim 11 wherein the geometry of the surface is a V shape with theopen end of the V toward the target surface.
 13. A method as in claim IIwherein the method further includes the step of minimizing convectiveand conductive energy between the surface and the target surface.
 14. Amethod as in claim 11 wherein the method further includes the step ofintroducing a partial vacuum between the surface and the target surfacefor reducing convection.
 15. A method for emitting radiant heat from asurface to a target surface, the target surface having an actualtemperature which is higher than the actual temperature of the surfacebut lower than the apparent temperature of the surface for achieving anet flow of radiant heat to the target surface comprising the steps of:configuring the geometry of the emitter's surface to project nondiffuseradiant emission patterns; providing the emitter surface with a highlyreflective surface for improving the projection of nondiffuse radiantemission patterns; and minimizing convective and conductive energybetween the surface and the target surface.
 16. A method as in claim 15further including the step of using a non-reflective target surface formaximizing the radiant heat absorbed by the target surface.
 17. A methodfor transferring radiant heat from outside an enclosure to a targetwithin the enclosure where the temperature of the target is higher thanthe temperature outside the enclosure, comprising the steps of:providing a surface in the enclosure in communication with heat energyoutside of the enclosure for radiating heat to the target, the surfacehaving a highly reflective surface for improving the projection ofnondiffuse radiant emission patterns; configuring the geometry of thesurface to project nondiffuse radiant emission patterns toward thetarget; and minimizing convective and conductive energy between thesurface and the target surface.
 18. A method as in claim 17 furtherincluding the step of surrounding the target with surfaces.
 19. A methodin claim 18 where the outside of the enclosure forms the outside surfaceof the target of a larger similar enclosure with otherwise the samefeatures.
 20. A method for recycling waste beat in a generation plantcomprising the steps of installing at least one radiant heat pump in thegeneration plant for absorbing heat outside the radiant heat pump toincrease the heat of a target within the heat pump where the target isat a higher temperature than the temperature outside the system.
 21. Aradiant heat pump device for transferring heat comprising: a surface foremitting energy radiation; a target surface in communication with thesurface for receiving energy from the surface, the target surface havinga higher temperature than the surface; and the surface having ageometrically modified surface for projecting nondiffuse radiantemission patterns towards the target surface.
 22. The heat pump of claim21 with the following added elements: means to deliver external heat tothe emitting surface; and means to remove heat from the target surfaceto outside of the device.
 23. A radiant heat pump as in claim 21 whereinthe surface has a polished metallic surface for improving the projectionof nondiffuse radiant emission patterns.
 24. A radiant heat pump as inclaim 21 wherein the convective and conductive transfer of energybetween the surface and the target surface is minimized.
 25. A radiantheat pump as in claim 21 wherein the geometry of the surface is a Vshape.
 26. A radiant heat pump as in claim 21 wherein the surfacesurrounds the target surface.
 27. A radiant heat pump as in claim 21wherein a second emitting surface surrounds the surface for projectingnondiffuse radiant emission patterns towards the surface.
 28. A radiantheat pump comprising: a hollow emitter assembly defining a vacuum sealedenclosure; a hollow cylindrical target disposed through the hollowemitter assembly for collecting radiation and for transporting theradiation to the exterior of the emitter assembly; and the emitterassembly having a plurality of emitting plates on the emitter assembly'sinner surface, the emitter plates facing the hollow cylindrical targetand the emitter plates having a smooth surface for reflecting radiationemitted from the emitter assembly to the emitter plates to the hollowcylindrical target.
 29. A radiant heat pump as in claim 28 whereinadjacent emitter plates form a V shape.
 30. A radiant heat pump as inclaim 28 wherein a second emitter assembly have internal emittingsurfaces surrounds the hollow emitter assembly for projecting nondiffuseradiant emission patterns towards the emitter assembly.
 31. A radiantheat pump comprising: an inner hollow emitter assembly defining a vacuumsealed enclosure; an outer hollow emitter assembly in communication witha heat source, the outer hollow emitter assembly concentricallyenclosing the inner emitter assembly for transferring heat to the inneremitter assembly; a hollow cylindrical target disposed through the inneremitter assembly for absorbing heat from the inner emitter assembly andfor transporting the absorbed heat outside of both emitter assemblies;each emitter assembly having a plurality of emitting plates on eachemitter assembly's inner surface, the emitter plates on the innersurface of the inner emitter assembly facing the hollow cylindricaltarget and having a smooth surface for reflecting heat emitted from theinner emitter assembly to the emitter plates to the hollow cylindricaltarget; and the emitter plates on the inner surface of the outer emitterassembly facing the inner emitter assembly and having a smooth surfacefor reflecting heat emitted from the outer emitter assembly to theemitter plates to the inner emitter assembly for increasing heat flow tothe inner emitter assembly thereby increasing heat flow by radiation tothe hollow cylindrical target.
 32. A radiant heat pump comprising: anouter element with an inner surface and an outer surface, a first endand a second end; an inner element within said outer element; aplurality of V-shaped emitting units disposed about the inner surface ofsaid outer element, said emitting units being capable of emittingradiant heat towards said inner element; an end cap disposed at each endof said outer element, and connecting said outer element and said innerelement; a fluid within said inner element, capable of transmitting heataway from said inner element; a vacuum disposed between said outerelement and said inner element, and a fluid disposed about said outerelement.
 33. A radiant heat pump as in claim 32 wherein said outerelement is an elongated cylinder and said inner element is an elongatedcylinder concentric with said outer element.